While much has recently been learned about the structure and function of synapses, relatively little is now known about how they develop and are maintained. Two of the major questions in the study of the development of the central nervous system are related to the areas of specificity and plasticity. It is the latter quality which we wish to pursue here. The present proposal is directed towards study of early environmental influences on the development of brain morphology and behavior. It is concerned most directly with perceptual capacities, specifically with how visual pattern perception is modified by selective postnatal experience and how such environmental influences on behavior are mediated by morphological changes, as revealed by the Golgi technique. Additionally, specific tiae periods in postnatal ontogeny during which early visual stimulation is necessary for normal morphological and behavioral development will be studied. Finally, factors involved in recovery of function after environmental deprivation will be studied and correlated with further morphological change.